The global objective of this Mentored Patient-Oriented Research Career Development Award is to build my career as an academic physician-scientist and make the transition to become an independent investigator. To accomplish this goal, together with my mentor, i have developed a tightly integrated plan including cutting edge science, and advanced training in the techniques of patient-oriented research. By participating in the K30 Curriculum in Patient-Oriented Research at UT Southwestern leading towards a MPH degree, I will receive in-depth instruction in research design, protection of human subjects, grantsmanship, and advanced level biostatistics. From my mentor and advisory committee, made up of senior scientists both at UT Southwestern and at the Brigham and Women's Hospital, I also will acquire critical new research skills regarding renal/neurohormonal mechanisms of blood pressure control, reproductive endocrinology, and clinical orthostatic intolerance. My research plan focuses on the mechanisms underlying gender differences in orthostatic tolerance, including neurohumoral influences on cardiovascular control processes and physical characteristics (primarily cardiac size and function) that determine orthostatic distribution of central blood volume. Menstrual cycle variability in young women, and differences among men, women, and women with chronic orthostatic intolerance (Postural Orthostatic Tachycardia Syndrome, or "POTS") will be examined. Finally, a specific intervention (exercise training) will be studied as treatment for patients with POTS and compared with standard pharmacologic therapies (13-blockers and volume expanders). Autonomic neural control of hemodynamic and sympathetic responses to the Valsalva maneuver, static handgrip, a cold pressor test, and prolonged head-up tilt will be investigated; the venoarteriolar response and neurohumoral responses to a long-term standing will be examined. After completion of the proposed project, we will know whether gender-specific factors such as the menstrual cycle or physical factors influencing cardiac size and function are among the determinants for orthostatic intolerance in young women, and whether physical exercise training can be considered an effective non-pharmacologic treatment for patients to improve their orthostatic tolerance. The combination of advanced training in patient-oriented research and in-depth study of an important clinical problem will prepare me well for a career as an independent investigator.